Lewis & Short

excŭbātĭo, ōnis, f. [excubo], a watching, keeping watch.

  1. * I. Lit.: ab excubatione desistere, Dig. 49, 16, 3, § 6.
  2. * II. Trop.: perpetua pro dignitate et salute amicorum, Val. Max. 4, 7, 7.